Corrugated bulk containers typically comprise side and end walls formed of multiple corrugated layers laminated together to provide extra thickness. Closure flaps are provided which, when folded, comprise the top and bottom of the bulk containers. The closure flaps typically comprise fewer layers than the side and end walls and are folded into an overlapping relation with one another, providing a double thickness in the overlapping regions.
Conventionally, the closure flaps are separated from one another by a simple linear slot extending from an outer edge of the closure flaps to an inner edge of the closure flaps, in alignment and colinear with fold lines demarcating adjacent side and end walls. A problem with this conventional design is binding and bunching of the thick laminated walls at the corners of the container when the blank is folded, thus hampering the folding operation. These corners are also susceptible to fraying and tearing at the ends of these slots, resulting in a sloppy appearance.
U.S. Pat. No. 1,992,087 to Miller et al. and U.S. Pat. No. 2,317,223 to Rottman disclose the use of circular eyes or cutouts at closure flap corners. The Rottman cutouts are intended to reduce tearing. The circular eyes of Miller et al. purport to allow free rounding or bending of a transparent material without cracking, bulging or wrinkling. A problem with the use of circular cutouts between closure flaps of bulk containers is the creation of through-holes at the corners of the folded container, allowing partial exposure of the interior of the container.